Realign processor stream-name default to telemetry:teltonika

Stage discovered the wrong default at runtime: tcp-ingestion's compiled
default REDIS_TELEMETRY_STREAM is 'telemetry:teltonika' but processor's
was 'telemetry:t', so the two services were talking past each other —
tcp-ingestion publishing to one stream, processor reading another empty
one. The deploy stack now pins both to the same value via a shared env
var, but the processor's compiled default should also match so local
development and the integration test stay aligned with reality.

Changes:
- src/config/load.ts — default changed to 'telemetry:teltonika'
- .env.example — same
- test/config.test.ts — default-value assertion updated
- planning docs (ROADMAP, phase-1 README, tasks 03/08/10, phase-3 README) —
  occurrences of 'telemetry:t' replaced with 'telemetry:teltonika'

The deploy stack remains the single source of truth via the shared
REDIS_TELEMETRY_STREAM env var. Compiled defaults are belt-and-braces.

test/config.test.ts

@@ -52,9 +52,9 @@ describe('loadConfig — defaults', () => {
     expect(config.LOG_LEVEL).toBe('info');
   });
 
-  it('applies default REDIS_TELEMETRY_STREAM=telemetry:t', () => {
+  it('applies default REDIS_TELEMETRY_STREAM=telemetry:teltonika', () => {
     const config = loadConfig(validEnv());
-    expect(config.REDIS_TELEMETRY_STREAM).toBe('telemetry:t');
+    expect(config.REDIS_TELEMETRY_STREAM).toBe('telemetry:teltonika');
   });
 
   it('applies default REDIS_CONSUMER_GROUP=processor', () => {